In Reply Dr van Rossum raises concern about our suggestion that 23andMe’s PGS could be used under the supervision of a physician once the analytical validity of the test has been established. We wholeheartedly agree that data describing the clinical validity of genetic tests, like the PGS, would clarify their role in medical practice. The clinical validity of the PGS consists of 2 components: the test must predict an individual’s risk of disease using data derived from studies of genetic association, and once this is done accurately, physicians must know how to use this information in the clinical setting. Van Rossum rightly points out that the PGS falls short on both of these components.